Materials — Quiz 5

Questions in this quiz (10)

1. In ACI concrete mix design, the bulk volume of coarse aggregate per unit volume of concrete is $$0.62$$ based on the fineness modulus of the fine aggregate. If the dry-rodded unit weight of the coarse aggregate is $$1650\ \text{kg/m}^3$$, calculate the mass of coarse aggregate required per cubic meter of concrete.

   • 920 kg/m³
   • 1,023 kg/m³
   • 1,089 kg/m³
   • 1,210 kg/m³

2. A spring with a stiffness of $$600\ \text{N/mm}$$ is compressed by $$10\ \text{mm}$$. Calculate the elastic potential energy stored in the spring.

   • 18 J
   • 30 J
   • 45 J
   • 60 J

3. A water-reducing admixture is specified at a dosage of $$220\ \text{mL}$$ per $$100\ \text{kg}$$ of cement. If the concrete mix contains $$420\ \text{kg/m}^3$$ of cement, calculate the volume of admixture required per cubic meter of concrete.

   • 720 mL/m³
   • 840 mL/m³
   • 924 mL/m³
   • 1,020 mL/m³

4. A concrete batch contains $$320\ \text{kg}$$ of cement, $$160\ \text{kg}$$ of water, $$720\ \text{kg}$$ of fine aggregate, and $$1080\ \text{kg}$$ of coarse aggregate. If the yield is $$0.95\ \text{m}^3$$, calculate the unit weight of fresh concrete.

   • 2,200 kg/m³
   • 2,390 kg/m³
   • 2,460 kg/m³
   • 2,520 kg/m³

5. In a transformed section analysis of a reinforced concrete beam, the steel reinforcement has an area of $$1000\ \text{mm}^2$$ and the modular ratio $$n=9$$. Calculate the transformed area of the steel.

   • 8,000 mm²
   • 9,000 mm²
   • 10,000 mm²
   • 11,000 mm²

6. In a Blaine air permeability test, a reference cement has a specific surface of $$320\ \text{m}^2/\text{kg}$$ with a flow time of $$65\ \text{s}$$. A test cement under the same conditions has a flow time of $$82\ \text{s}$$. Assuming specific surface is proportional to the square root of time, calculate the fineness of the test cement.

   • 345 m²/kg
   • 360 m²/kg
   • 378 m²/kg
   • 402 m²/kg

7. Calculate the heat energy required to raise the temperature of a $$3.0\ \text{kg}$$ concrete specimen by $$40^\circ C$$. The specific heat capacity of concrete is $$900\ \text{J/(kg\cdot K)}$$.

   • 86.4 kJ
   • 96.0 kJ
   • 108.0 kJ
   • 120.0 kJ

8. In a freeze-thaw durability test, a concrete specimen completes $$250$$ cycles with a relative dynamic modulus of $$88\%$$. Calculate the durability factor using $$DF=(P\times N)/M$$, where $$M=300$$ specified cycles.

   • 66%
   • 73%
   • 82%
   • 88%

9. A green wood sample weighs $$920\ \text{g}$$. After oven drying, it weighs $$560\ \text{g}$$. Calculate the moisture content on a green (wet) basis.

   • 34%
   • 39%
   • 45%
   • 64%

10. A compacted asphalt specimen has a bulk specific gravity $$G_{mb}=2.320$$ and a maximum theoretical specific gravity $$G_{mm}=2.460$$. Calculate the percent air voids using $$VTM=100(1-G_{mb}/G_{mm})$$.

    • 4.1%
    • 5.7%
    • 6.2%
    • 7.0%